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The present invention relates to lifting devices as used in pickup trucks. More particularly, the present invention relates to apparatus whereby heavy loads can be moved from a location outside of the bed of a pickup truck into the interior of the pickup truck bed and, in particular, in a desired location within the bed of the pickup truck.
For many years, the advantages of providing a cargo carrying vehicle such as a truck with a lift gate have been recognized. As is well known, lift gates are gates which not only close the rear of the bed of the vehicle, but which, when in the housing position, may be moved between a first position wherein they are an extension of the truck bed and a second position resting on the underlying terrain. Cargo may be loaded on or removed from the gate while in the latter position or loaded into or unloaded from the vehicle when in the former position. Conventionally, some sort of motor is utilized to drive the lift gate between the two positions. There is some sort of linkage which maintains the upper surface of the gate in a generally horizontal plane during such movement to prevent cargo on the gate from falling off.
Lift gates are generally not suited for small or medium sized cargo-carrying vehicles because the linkage and the drive system for moving the gate between upper and lowered positions was adapted to be located wholly below the plane of the truck bed. This, in turn, requires that the bed of the truck be located relatively high above the underlying terrain to provide the requisite ground clearance. As a result, this is limited to relatively large cargo-carrying vehicles with high road clearances.
Another problem with lift gates is that the cargo is only brought to the very end of the bed of the truck. As a result, it is still necessary to move the heavy load from the lift gate into the bed of the truck. Such movement of heavy loads can be inconvenient and difficult to accomplish. In other circumstances, the heavy load must be lifted a small distance so as to bring the load into proximity onto the lift gate. Once again, workers must be prepared to lift the load, at least a small distance, so as to place the load in its desired position on the lift gate. In many circumstances, the heavy load is only delivered to the very back of the bed of the pickup truck. As a result, the pickup truck will have an unbalanced load heavily oriented toward the rear of the truck. Such unbalanced loads can create driving hazards. Additionally, and furthermore, the lift gates only allow the load to be delivered toward the rear of the bed of the pickup truck. When additional heavy loads must be introduced into the bed, there is often a lack of space for such loads since the initial loads have not been moved toward the forward end of the bed.
In other circumstances, cranes have been proposed for use on such pickup truck beds. Unfortunately, these cranes are often unwieldy devices which prevent the load from being adequately delivered into the interior of the vehicle. In certain circumstances, the cranes will present a structure which extends outwardly above the top of the truck body. As a result, damage can often occur during the movement of the truck with these outwardly extending projections. Additionally, and furthermore, these cranes also fail to deliver the load where it is best desired, i.e. toward the forward end of the bed. These rear-mounted cranes often lift the load to a position whereby the worker can push the load into the rear portion of the pickup truck bed. Once again, limited loads and unevenly distributed loads will result.
In the past, various patents have issued in the past for the loading of the bed of pickup trucks. U.S. Pat. No. 3,637,097, issued on Jan. 25, 1972 to R. R. Horowitz, describes a power-operated tailgate. This power-operated tailgate mechanism has pairs of bell-crank lever arms pivotally mounted on the bed surface and outer ends pivotally connected to a support arm which is attached to the tailgate. The relationship of the pivotal connections is such as to provide a parallelogram linkage for the purpose of maintaining the tailgate surface in a load-carrying attitude during the elevating and lowering movement of the tailgate.
U.S. Pat. No. 3,700,123, issued on Oct. 24, 1972 to Q. D. Corley, Jr., describes a lift frame for attachment to the truck bed. This lift frame includes a tubular horizontal base having integral transverse brackets for attachment to the truck frame and having upright end posts securely welded to the tubular member. A hinged lift platform is provided which is swingably supported by parallelogram arms on the frame end posts. A torque bar connects the lift arms. A hydraulic power cylinder connects one lift arm and one corner post to swing the lift platform between the upper position in the plane of the truck bed and a lower ground position.
U.S. Pat. No. 4,265,585, issued on May 5, 1981 to W. H. Hawkins, teaches a loading device for vehicle beds wherein a transversely aligned boom members have an extensible inverted U-shaped member adjustably carried on free ends thereof. The U-shaped member is pivotally secured on a supporting frame and operated by fluid-operated cylinder assemblies which are pivotally connected on one end to a respective boom and on the other end to an upright frame member carried forwardly in the vehicle. The cylinder assemblies ascend above the top of the bed of the pickup truck so that the U-shaped member will rest in a stowed position above the truck bed.
U.S. Pat. No. 5,119,961, issued on Jun. 9, 1992 to L. E. Runn, describes a removable, truck-mounted crane with both an inclined boom for high lift and a horizontal telescoping boom for extended reach beyond the truck. The crane has two winches which can be routed to either boom. A rolling storage stand with winches is used to support the truck tailgate while enabling one person to install or remove the crane from the truck.
U.S. Pat. No. 5,641,262, issued on Jun. 24, 1997 to Dunlop et al., describes a hydraulic lift apparatus whereby the tailgate of the pickup truck can be moved from a lowered position to an upper position.
U.S. Pat. No. 6,019,567, issued on Feb. 1, 2000 to Lutkas et al. describes a slidable load lifting system which can be retracted into the pickup truck. This load lifting apparatus includes a base frame member attached to the truck bed. This base frame member supports a substantially planar roller platform member slidably therein. A pair of elongate rail members extends in parallel and is adapted to engage a set of roller wheels provided on the bottom of the roller platform member. A substantially planar lift platform member is operatively connected to the other roller platform member through a set of parallelogram linkages which allow the lift platform to be moved between a raised position coplanar with the roller platform and a lowered position out of the plane of the roller member for convenient loading of the lift platform at ground level.
U.S. Pat. No. 6,234,741, issued on May 22, 2001 to S. P. McDaniel, describes a forklift for pickup truck. This forklift device is adapted to be installed within the bed of a conventional pickup truck. The horizontal movement of the fork is provided by movement of the truck. When the device is not in use, it is disposed above the forward portion of the truck bed.
It is an object of the present invention to provide a lifting apparatus for use in a pickup truck which allows loads to be delivered into the bed of the pickup truck.
It is another object of the present invention to provide a lifting apparatus which allows heavy loads to be placed in any desired position within the bed of the pickup truck.
It is another object of the present invention to provide a lifting apparatus which avoids the use of power-operated tailgates.
It is another object of the present invention to provide a lifting apparatus which can be stowed entirely within the interior of the bed of the pickup truck.
It is still a further object of the present invention to provide a lifting apparatus which entirely avoids the need for human lifting activity.
It is still another object of the present invention to provide a lifting apparatus which provides an entire 180xc2x0 range of motion of the lifting arm relative to its pivot point within the bed of the pickup truck.
It is still another object of the present invention to provide a lifting apparatus which is easy to use, relatively inexpensive, easy to install and simple to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.
The present invention is a lifting apparatus comprising a pickup truck having a bed with a pair of side walls on opposite sides of the bed, a lifting apparatus having a generally U-shaped configuration with one side pivotally connected to one of the side walls and an opposite side pivotally connected to another of the side walls and a cylinder means connected to at least one of the sides of the lifting bar. The cylinder means serves to pivot the lifting bar between a first position extending outwardly between the end opening of the pickup truck bed and a second position stowed entirely within the bed of the pickup truck such that the lifting bar has an end adjacent the forward wall of the pickup truck bed. A linkage connects the cylinder means to the side of the lifting bar generally adjacent to the pivotal connection of the lifting bar to the side of the bed.
The linkage of the present invention includes a first arm having a first end pivotally connected to the side of the lifting bar and a second end pivotally connected to the cylinder means. The linkage also has a second arm having a first end pivotally connected to the cylinder means and a second end pivotally connected to the side wall of the pickup truck bed. The second end of the first arm is pivotable relative to the second arm.
In the present invention, the cylinder means comprises a cylinder pivotally connected at one end of the side wall of the bed and a piston rod translatable relative to the cylinder. The second end of the first arm and the first end of the second arm are connected to an end of the piston rod opposite the cylinder. The first end of the first arm has a pivot point positioned outwardly of one surface of the side of the lifting bar. This pivot point is positioned away from the pivotal connection of the lifting bar with the side wall. The second end of the second arm has a pivot point with the side wall positioned on a side of the pivotal connection of the lifting bar with the side wall opposite to the pivot point of the first arm with the lifting bar. The pivot point of the second end of the second arm is positioned lower in the bed than the pivotal connection of the lifting bar with the side wall.
In the present invention, the lifting bar has a first side pivotally connected to one of the pair of side walls of the bed. The lifting bar has a second side pivotally connected to another of the pair of side walls. The lifting bar has a crossbar extending between the first and second sides at an end opposite the pivotal connections of the lifting bar with the pair of side walls. A lifting line can extend downwardly from the crossbar so as to connect to a load to be lifted.
In the present invention, the cylinder means comprises.a first cylinder pivotally connected to one of the pair of side walls, a first piston rod translatable in and extending from the first cylinder and having an end opposite the first cylinder interconnected to the first side of the lifting bar, a second cylinder pivotally connected to another of the pair of side walls, and a second piston rod translatable in and extending from the second cylinder so as to have an end opposite the second cylinder interconnected with the second side of the lifting bar.
The end of the pickup truck has a first wheel well and a second wheel well. The first cylinder is positioned above the first wheel well. The second cylinder is positioned above the second wheel well. The pickup truck has a tailgate pivotally affixed so as to open and close the end opening of the truck. The lifting arm and/or the tailgate has a switch means affixed thereto for stopping a movement of the lifting bar when the lifting bar approaches the top of the tailgate. A control means is connected to the cylinder means. This control means serves to actuate the cylinder means from moving the lifting bar between its first and second positions.
In the preferred embodiment of the present invention, the cylinder means is a hydraulic cylinder.